#include<stdio.h>
#include<math.h>
int main()
{float integral(float(*)(float),float,float,int);
 float fsin(float);
 float fcos(float);
 float fexp(float);
 float a1,b1,a2,b2,a3,b3,c,(*p)(float);
 int n=20;
 printf("input a1,b1:");
 scanf("%f,%f",&a1,&b1);
 printf("input a2,b2:");
 scanf("%f,%f",&a2,&b2);
 printf("input a3,b3:");
 scanf("%f,%f",&a3,&b3);
 p=fsin;
 c=integral(p,a1,b1,n);
 printf("The integral of sin(x) is:%f\n",c);
 p=fcos;
 c=integral(p,a2,b2,n);
 printf("The intrgral of cos(x) is:%f\n",c);
 p=fexp;
 c=integral(p,a3,b3,n);
 printf("The integral of exp(x) is:%f\n",c);
 return 0;
 }
 float integral(float(*p)(float),float a,float b,int n)
 {int i;
  float x,h,s;
  h=(b-a)/n;
  x=a;
  s=0;
  for(i=1;i<=n;i++)
  {x=x+h;
   s=s+(*p)(x)*h;
   }
   return(s);
 }
float fsin(float x)
{return sin(x);}

float fcos(float x)
{return cos(x);}

float fexp(float(x))
{return exp(x);}
